The factors driving the ebbs and flows of mortgage rates are largely unknown to the general population. You may be inclined to blame -- or commend -- your mortgage lender for the low or high rate she offers you; but, in actuality, it's not her decision. Today, the true drivers of mortgage rates are the investors in the secondary market.
To the layman's eye, mortgage rates seem to move up and down without explanation. But, just like the ocean tides that wash up and back by the pull of the moon's gravity, mortgage rates have their own driving force, even if they have a less cosmic source.